Sensorimotor and auditory central conduction time in locked-in syndrome.

Motor evoked potentials (MEPs) following magnetic cortical stimulation, somatosensory evoked potentials from median nerve (SEP) and auditory brain-stem responses (ABR) were recorded in a patient with locked-in syndrome during the acute and chronic phases of the clinical course. During the acute phase both ABR and SEP were normal. The MEP from the right upper limb showed a delayed and low voltage potential, while that from the left upper limb was absent. The CT scan showed a ponto-mesencephalic hypodensity. In the chronic phase the MEP from the left upper limb had reappeared and showed a normal latency, while the one from the right upper limb worsened; at that time a new small left fronto-parietal hypodensity had appeared on CT scan. The combined use of MEP, SEP and ABR was able to confirm that the brain-stem damage involved the pyramidal but spared the lemniscal pathways, while MEP changes during the clinical course appeared to reflect both clinical and radiological findings.